Update tox to remove py27 target

Change-Id: I26aa26b87d731946dac12da5a356b757551925cf

.stestr.conf

@@ -0,0 +1,3 @@
+[DEFAULT]
+test_path=./unit_tests
+top_dir=./

tox.ini

@@ -2,9 +2,8 @@
 # This file is managed centrally by release-tools and should not be modified
 # within individual charm repos.
 [tox]
-envlist = pep8,py27,py3{5,6}
+envlist = pep8,py3
 skipsdist = True
-skip_missing_interpreters = True
 
 [testenv]
 setenv = VIRTUAL_ENV={envdir}
@@ -17,9 +16,6 @@ commands = ostestr {posargs}
 whitelist_externals = juju
 passenv = HOME TERM AMULET_* CS_API_*
 
-[testenv:py27]
-commands = /bin/true
-
 [testenv:py35]
 basepython = python3.5
 deps = -r{toxinidir}/requirements.txt
@@ -30,6 +26,11 @@ basepython = python3.6
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 
+[testenv:py3]
+basepython = python3
+deps = -r{toxinidir}/requirements.txt
+       -r{toxinidir}/test-requirements.txt
+
 [testenv:pep8]
 basepython = python3
 deps = -r{toxinidir}/requirements.txt